1. Field of the Invention
The present invention relates to an improvement in an electromagnetic coupling device. In more detail, the present invention relates to an electromagnetic coupling device comprising, an input shaft hub, an output shaft hub, an electro-magnet disposed at the side of the input shaft hub, an armature attached through a spline coupling means to the output shaft hub so as to be kept spaced apart from the input shaft hub at a predetermined gap when the electro-magnet is not excited, and a ring shaped flat spring which normally urges the armature toward the output shaft hub.
2. Description of the Prior Art
Heretofore, there has been proposed, for example, an electromagnetic coupling device having a structure as shown in FIG. 1, which comprises, an input shaft hub 1, an output shaft hub 2, an electro-magnet 3 disposed at the side where said input shaft hub 1 is mounted, an armature 6 attached through a spline coupling 5 to the output shaft hub 2 which is normally urged by a leaf spring 4 so as to be spaced apart from the input shaft hub 1 at a predetermined gap g when the electro-magnet is not excited, whereby the electro-magnet 3, when excited, can attract the armature 6 toward the input shaft hub 1 against the spring force imparted by the spring 4 so that a torque given by the input shaft hub 1 can be transmitted by the spline coupling 5 to the output shaft hub 2.
In the conventional electromagnetic coupling device shown in FIG. 1, it is required for such coupling device for effecting axial displacement of the armature 6 by means of a spring action given by the leaf spring 4, that both the spring 4 and the armature 6 must be joined together by either one of the following means as mentioned below,
1)caulking with rivet or rivets, or PA1 2)screw setting with screw or screws.
However, the caulking work according to the item 1) requires drilling of the armature to form a through hole or holes and subsequent rivetting work, while the screw setting according to the item 2) requires machining for making both screws and tapped hole(s) in an armature piece, in addition, troublesome assembly of these related parts is also required.